1. Field of the Invention
The invention relates to components for an improved system for pick-up impression making at a dental implantation site, comprising an impression coping and an abutment replica. The invention also relates to a set comprising an abutment and an impression coping and to a method for impression making.
2. Description of Related Art
Dental implant systems are widely used for replacing damaged or lost natural teeth. In such systems, an implant is placed in the jaw of a patient in order to replace the natural tooth root. An abutment structure comprising one or several parts may then attached to the implant in order to build up a core for the part of the prosthetic tooth protruding from the bone tissue, through the soft gingival tissue and into the mouth of the patient. On said abutment, the prosthesis or crown may finally be seated.
The final prosthesis must be sized and configured so as to naturally fit with the remaining teeth of the patient, both for functionality and aesthetics. To this end, a dental technician needs to try out a proper prosthesis for the individual patient, using a model of the jaw of the patient, said model including the implant and possibly an abutment structure. To provide such a model, so-called master cast modelling techniques are used.
One category of such modelling techniques is the so-called “pick-up” method. A pick-up method could be described by the following subsequent steps:                An impression cap is placed on the implant and/or the abutment.        An impression material is applied to the jaw, such that said impression cap is embedded in the impression material.        The impression material is removed from the jaw, bringing along the impression cap still being embedded in the impression material. The impression material now has the inverse form of the jaw with the impression cap at the site of the implant/abutment.        A replica replicating the shape of the implant and/or abutment is inserted into the embedded impression cap, in the same manner as the original implant and/or abutment was connected to the impression cap.        A molding material is poured into the inverse form of the jaw made out of the impression material and around the replica and let to harden.        The impression material is removed from the hardened molding material, said molding material now forming a true, or non-inverse model of the jaw with the replica replacing the original implant/abutment.        
In the following, reference will be made to some prior art documents describing pick-up methods or components to be used therewith.
U.S. Pat. No. 6,068,478 (Grande et al.) discloses an impression system including an impression cap for transferring an end, protruding from a human tissue structure, of an implant which is fitted in the human body, including possible superstructures, to a master cast. The outwardly directed implant end has an undercut contour on its outside, and the impression cap has a geometry which complements the undercut contour and engages therein. The undercut contour is formed either by an implant geometry tapering in a trumpet shape towards the implant bed, or by a recess near the implant end.
In said U.S. Pat. No. 6,068,478 (Grande et al.), a superstructure part is described to be screwed into the implant such that an abutment of the superstructure is projecting above the implant shoulder. For taking an impression of the mouth situation to a finished master cast, a slide sleeve is first of all pushed onto the conical superstructure. Then, an impression cap is pushed over the slide sleeve. At the very bottom, the impression cap has a cap shoulder, which is complementary to the implant shoulder. On the outside, the cap shoulder is surrounded by an elastic snap element directed inwards, so that it can snap over the implant shoulder and releasably grip an undercut contour on the implant head. An impression tray filled with impression compound is now pressed onto the implantation site. After withdrawing the impression tray, the impression cap and the slide sleeve remain embedded in the impression compound, and the impression is obtained. An analogous manipulation implant having a shape corresponding to the conical superstructure is now pushed into the slide sleeve. Finally, a manipulation shoulder sleeve, having a manipulation shoulder corresponding to the implant shoulder is pushed over the manipulation implant until the manipulation shoulder is held by the snap element of the impression cap. Modelling compound is lastly poured onto the impression and the master cast is obtained.
In said U.S. Pat. No. 6,068,478 (Grande et al.), another impression method is used if another type of superstructure, for example an angled superstructure is attached to an implant. In this case, an impression cylinder is screwed onto the superstructure and a laterally open impression cap is pushed onto the superstructure such that is grabs the implant shoulder. The impression is taken using the impression tray filled with impression compound, which impression is obtained after withdrawing the impression tray, and in which the impression cap and a hollow space according to the impression cylinder and the conical superstructure remain behind. In the next step, the impression cylinder is pushed into its hollow space and the manipulation shoulder sleeve is attached, and modelling compound is then filled through the manipulation shoulder sleeve so that the whole hollow space is filled up. Modelling compound is now poured onto the impression and, after removing the impression tray in which the impression cylinder remains, the finished mater cast is obtained.
It is further mentioned that the slide sleeve might be omitted if the hollow space remaining in the impression cap, and left by the selected abutment inside the impression cap, is filled with impression compound. Also, the slide sleeve and the impression cap may be combined and designed as one piece.
U.S. Pat. No. 6,159,010 (Rogers et al.) discloses a dental coping for placement over an abutment post that is attached to and protruding above a dental implant. The coping includes a base portion having an internally tapered surface for mating with a support surface of the implant. A wall extends away from the base portion for enveloping the abutment post. The wall includes at least one aperture for allowing wax material to pass therethrough when taking an impression of the implantation site.
U.S. Pat. No. 5,688,123 (Meiers et al.) discloses a transfer cap for dental implants that is to be used when taking an impression for forming a master cast model. This transfer cap is adapted in form and size to the built-up part or abutment of the implant and carries one or more resilient flaps extending over the shoulders of a conical area of the built-up part.
WO 99/29255 (Morgan) discloses an abutment analogue having a head portion being formed with retention means such as an annular groove.
EP 0 190 670 (Lustig) discloses a prefabricated abutment that may be used in combination with a prefabricated sleeve-like coping which is telescopically mated to the post.
An object of this invention is to provide components for a system for improved function when using pick-up impression methods, and a method using said components.